Manufacturers of rubber reinforced articles have long realized the importance of the interfacial adhesion of the metal reinforcement of its rubber environment. For example, many tire manufacturers use various cobalt salts as bonding promoters in their steel cord wire coats. The bonding promoters are added through compounding. To achieve a maximum bonding strength, excessive amounts of cobalt salt are added to the wire coat. Since only a very small portion of the cobalt salt was engaged in the rubber-metal interfacial bonding reaction, most of the cobalt salts remained in the compound as excess cobalt without any contribution to the bonding. Cobalt is expensive and may even cause aging problems of the rubber when used in excess.
WO 99/55809 relates to the drawing of wire with the use of a cobalt and/or nickel salt suspension as an adhesive, lubricating and suspending agent. Unfortunately, due to subsequent processing of the wire, levels of the cobalt salt are reduced from the surface of the wire.
U.S. Pat. No. 5,221,559 relates to a method of treating tire cord with a solution of at least one organic compound containing a hydroxyl groups. The solution further contains at least one cobalt and/or nickel compound. In Example 5 of this patent, a brass-plated cable is treated with a paraffin oil containing 1 percent by weight of cobalt naphthenate.